The present invention relates generally to digital multimeters. More particularly, the invention relates to a digital multimeter having an improved rotary switch assembly.
Digital multimeters (DMMs) function to measure a number of electrical parameters as needed for service, troubleshooting and maintenance. Such parameters may include AC voltage and current, DC voltage and current, resistance and continuity. In some cases, a DMM may measure other parameters such as capacitance and temperature.
A DMM will often be configured as a hand-held unit having a rotary knob by which various functions are selected. A plurality of lead jacks are provided in the case (i.e., housing) of the unit for connection of test leads. The specific jack used may depend on the function that has been selected. An LCD display provides a reading of the tested parameter.
Various electronic components are mounted to a printed circuit board located inside the case of the DMM. A rotary switch having multiple contact pairs may be mounted to the printed circuit board. When the selector knob is rotated by a user, the contact pairs are moved into or out of engagement with pairs of contact terminals located on the surface of the printed circuit board itself. As a result, a galvanic connection between the terminal pairs will be made as necessary for the selected function. The terminal pairs are formed through suitable printed circuit technology as conductive pads on the printed circuit board.
Details regarding the construction and operation of multimeters may be discerned from U.S. Pat. Nos. 7,034,517, 6,466,003 and 6,043,640, incorporated herein by reference.